Control system



C. B. CONNELY.

CONTROL SYSTEM.

APPLlCATlON FILED NOV.23, 1921.

PatentedJuly 25, 1922.

Inventor! Charles B. Connely, y

His Attorney.

UNITED STATES PATENT OFFICE.

CHARLES B. CONNELY, OF SCOTIA, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

CONTROL SYSTEM.

Specification of Letters Patent.

Patented July 25, 1922.

To all whom it may concern:

Be it'known that I, CHARLES B. CONNELY, a citizen of the United States, residing at Scotia, in the county of Schenectady, State of New York, have invented certain new and useful Improvements in Control Systems, of which the following is a specification.

My invention relates to an improved system and apparatus forthe control of electric translating devices whereby the devices are protected from abnormal or dangerous conditions.

lVhere controllers, such as drum controllers, are provided for regulating the current taken by translating devices, it is frequently desirable to avoid interrupting the main circuit at the controllers, and it is desirable to interrupt the circuits by means of electromagnetic switches under the'control of the controllers and under the control of the current taken by one or all of the translating devices. Arcing and burning at the controllers are thereby prevented. \Vhere a plurality of controllers are provided for regulating a plurality of translating devices, such for instance as the motors of a crane or an electrically operated ore bridge, it is desirable that the connection of all of the translating devices to the source of supply be interru ited in case the current taken by one or all 0 the devices is in excess of predetermined values; and it is desirable that in case the connection to the source is thus opened, it will be prevented from being reclosed until after all of the controllers are returned to their respec tive off positions.

The present invention is directed to a simplified system of the above indicated character. In carrying the invention into effect, an electromagnetic line switch is provided in a common conductor from the source of supply for all of the translating devices, and a separate electromagnetic lino switch in a separate return conductor to the source is provided for each of the separate translating devices. The electromagnetic line switch in the common conductor is normally energized and closed, and in case an abnormal condition occurs, such as an overload, this switch is antomatically opened as well as the line switch or switches in the return conductors and the switches are prevented from being reclosed until after all of the controllers are in their respective oif positions. The arrangement for effecting this result involr'es the use of an electromagnetic relay for controlling winding of the line switch in the common conductor. The connections are such that when the connection of the translating devices to the source of supply is automatically opened, the winding of this relay is connected across the contacts of the line switch in the common conductor and in series with at least one of the windings of a line switch in a return conductor. The closing of the line switch in the common conductor is prevented until the controllers are all in their respective off positions, since after the line switches are automatically opened, the relay is energized through at least one of the controllers to maintain the line switch in the common conductor deenergized.

For a better understanding of the invention, reference is had to the accompanying drawing wherein I have shown an embodiment of the invention for the purpose of explaining the principles thereof. Referring to the drawing, the separate electric translating devices are shown as the armatures 10, 11 and 12 of separate electric motors which may be used for controlling the operation of a crane, an ore bridge or the like. Each of I these motors is separately controlled by means of its respective individual controller 13, 14 or 15. An electromagnetic line switch 16 is provided in a common conductor for all of the motors from the source of supply 17, and the electromagnetic line switches 18, 19 and 20 are provided in the respective return coiuluctors for the motors 10, 11 and 12; The current responsive relay 21 is included in the common conductor from the source of supply, and the current limit relays 22, 23 and 24 are provided in the respective return conductors of the motors 10, 11 and 12. These relays are provided forautomatically opening the connection of the motors to the source of supply in case the current taken by an individual motor or the current taken by all of the motors is in excess of a predetermined value or values. The electromagnetic relay 25 is provided for controlling the winding of the line contactor 16 in the common conductor, and this relay also effects a control of the line switches 18. 19 and 20 in the respectlve return conductors.

As thus constructed and arranged and with the parts in their respective positions as shown in the drawing, the operation of my invention is as follows: In order to start any one or all of the controlled motors,

.the disconnecting switch 26 is first closed.

when the controller 14 is turned to its first operative position and the line contactor 20 being energized to close when the controller 15 is turned to its first operative position. In case an overload should occur in any one or all of the motor circuits, the line switches are automatically opened and are prevented from being reclosed until all of the controllers or master switches are returned to their respective off positions. Thus, for instance, in case an overload should occur in the motor 10, the current relay 22 will be energized to open its contacts, thereby deenergizing the windings of the line contactors l6 and 18. When this happens, the current relay 22 will drop and close its contacts, but the line switches will not thereby be automatically reclosed, since the relay 25 will be energized through a circuit including the coil of the current relay 21, controller 13, conductor 28, winding of contactor 18, through the contacts of the current relays 21, 22, 23 and 24 to the other supply conductor. The winding of the relay 25 is thereby connected across the contacts of the line contactor 16 in series with the winding of the contactor 18 across the supply circuit, and this relay will be energized to pick up its contact member and thereby maintain open the circuit of the line contactor 16. through the winding of the line contactor 18 will be insufficient to energize this contactor to close, and the connection of the motor 10 to the source of supply is thereby prevented until the controller 13 is returned to the off position, that shown in the drawing, thereby opening the circuit for the winding of the relay 25 and the Winding of the contactor 18. The relay 25 is thereby permitted to drop its contacts and energize the line contactor 16 to close. The line contactor 18 in the return conductor may be reenergized by returning the controllerto an operative position.

In case all of the controllers 13, 14 and 15 had been turned to operative positions, and an overload should occur in any one or all of the motors, the relay 25 is similarly energized so as to hold open the circuit of the line contactor l6 and prevent automatically The current which flowsv the reclosing of the line switches until after all of the controllers are first returned to their respective off positions.

One of the advantages of my arrangement is that the contactors 16, 18, 19 and 20 and the current relays 21, 22, 23 and 24 may all be located in an enclosure in any convenient place at a distance from the motors and their respective controllers, and the only control wires running to the respective controllers are the single control wires for the respective line contactors in the return conductors, the single common main conductor and the individual main return conductors. A simplification of the wiring is thereby made possible. A further feature of advantage arises from the fact that the interruption of the circuits for the translating devices, in this case the electric motors, always occurs at the contacts of the electromagnetic line switches, and the controllers are never called upon to interrupt the electric circuits. The controllers may thereby be relatively small, since the current required to be interrupted by a controller is one of the principal factors in determining the size of the controller.

In accordance with the provisions of the patent statutes, I have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, but I desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means. I

What I claim as new and desire to secure by Letters Patent of the United States, is

1. The combination with a plurality of electric translatin devices, ofa separate controller for each of said devices, a normally closed electromagnetic line switch under the control of all of the said controllers in a common conductor for the said translating devices, a separate normally open electromagnetic line switch under the control of its corresponding one of said controllers in each of the separate return conductors for said devices, an electromagnetic relay having its winding connected across the circuit making contacts of the said line switch in the common conductor, current re sponsive means, and connections whereby the operation of the current responsive means deenergizes the said line switches and the i said relay is energized to maintain the said line switch in the common conductor in the open position until all of the said controllers are first returned to their respective off positions.

2. The combination with a plurality of electric translating devices of a common conductor for the said devices and a separate return conductor for each device, a separate controller for each of said devices. a normally energized contactor in the said common conductor, a separate contactor in each of said return conductors under the control of acorresponding cont-roller, an electromagnetic relay, current responsive means,

and connections whereby upon the operation of the current responsive means, the contactors which are closed are deenergized and opened and the Winding of said relay is energized through the Winding or windings of the contactors in the said return conductors 10 Which are thus opened to maintain open the Winding circuit of the said contactor 1n the said common-conductor until all of the said controllers are in their respective off posi- 'tions. 

